Two kinds of network modes, which are an infrastructure mode and an ad-hoc mode, are principally available in the network configuration of wireless LAN (Local Area Network) complying with the standards such as IEEE802.11. The infrastructure mode is such that a base station apparatus and a terminal apparatus are connected to each other and the terminal apparatus communicates with other terminal apparatuses via the base station apparatus. On the other hand, the ad-hoc mode is such that the terminal apparatuses directly communicate with each other without the need for the base station apparatus (See Non-patent Document 1, for instance).    [Non-patent Document 1] Masahiro MORIKURA and Shuji KUBOTA, “802.11 High-Speed wireless LAN text book”, pp. 60-63, Impress, Inc., Jul. 21, 2005, Japan